Abstract: Films are disclosed which are constituted essentially of iodides of heavy metals to which catalysts or sensitizing agents are added to make the films highly sensitive to light and current at room temperature, thus increasing the speed of writing and erasing cycles. The disclosure provides for producing and erasing images on such light and current sensitive films prepared on substrates such as ordinary paper or transparent non-reactive materials. Marking on the films is achieved by light e.g., laser beam and Xenon lamp, or electrical current. Exemplary erasing is done by application of heat. Several examples are disclosed of the formation of these films adherently on non-reactive surfaces.

Abstract: An imaged development process and materials wherein use is made of a photographic medium sensitive to ultraviolet radiations and formulated of an alkyl cellulose derivative and 7,7,8,8-tetracyanoquinodimethane.

Abstract: Photochromic aziridines of the formula ##STR1## wherein R.sub.1 and R.sub.2 taken separately are hydrogen, lower alkyl, phenyl, or ortho or para lower alkyl or lower alkoxy substituted phenyl, and wherein R.sub.1 and R.sub.2 taken together are alkylene having 4 to 7 carbon atoms, inclusive, are vapor deposited on a substrate, followed by application of a barrier coating which is substantially oxygen-impermeable to thereby provide a thermally stable optically erasable recording medium.

Abstract: Photochromic compounds are disclosed which are 3-furyl or 3-thienyl alkylidene succinic anhydrides or the corresponding succinimides. The compounds undergo reversible photocyclization on exposure to U.V. light in high yield and their cyclic forms are deeply colored making them suitable for a wide range of recording and display devices.